Concrete core drilling is a reliable and precise technique used to create cylindrical holes in concrete structures such as floors, walls, and ceilings. This method is used to accommodate new ducts, plumbing pipes, HVAC ducts, reinforcement, and other systems. Core drilling is also used to extract representative samples from completed asphalt or concrete installations for laboratory testing. In this blog post, we will discuss the process of core drilling and core sampling equipment, why and how asphalt and concrete cores are sampled, and the different laboratory tests that are performed.
We will also explore the advantages of core drilling and how it can be used to make perfect round holes in concrete structures. The process of cutting asphalt or concrete cores is similar, but the reasons for sampling each of these materials are substantially different. Portland cement concrete consolidates into its final position while in a plastic state and remains there as it cures over time through the hydration process and hardens, developing high compressive strength. ASTM C42 and AASHTO T 24 describe standard practices for the coring of hardened concrete elements and structures.
ASTM C823 guides the planning of examination and sampling of concrete structures. There are a wide variety of types of drills available today, but some do a better job than others when it comes to drilling holes in concrete or asphalt materials. Our job is not to drill holes, but to extract high quality and uniform cores for laboratory testing. This approach requires equipment with enough power and control to spin a drill bit straight through difficult materials.
A drill motor mounted in a robust frame with a precision feed, solidly anchored to prevent vibration, displacement and seizure of the drill bit, directly affects the quality of the sample. Asphalt pavement presents unique problems when coring. It is softer than concrete, but also more abrasive. The frictional heat from the diamond drill bits makes the asphalt softer and more viscous.
As the material softens, it can pinch the diamond drill bit, causing the drill to stop and damage the sample. Once the concrete has hardened sufficiently, it is easier to extract high quality, intact samples. Coring during the early stages of curing or when green can damage the sample. It seems counter-intuitive, but concrete coring bits use a softer bonding material to set the diamonds.
When cutting hard, brittle materials, diamonds fracture quickly and have a shorter life span. A softer bond matrix allows them to be washed away when they are no longer effective, exposing new diamonds to cut concrete more quickly. Concrete core drilling is an efficient way of cutting perfect round holes in concrete walls, floors, ceilings and other structures. This fine-tunes the concrete structure to accommodate amenities such as telephone lines, plumbing, HVAC ducts, sprinkler systems and more. Core drilling is known as a non-percussive process which means that the vibration caused by the drilling process is minimal causing minimal disturbance to surrounding areas. Water is also applied to the cut surface to cool and suppress harmful concrete dust.
The advantages of core drilling are many and it is a very useful way of cutting concrete with many applications. Commercially available units allow you to choose the right speed depending on the hardness of the concrete and size of hole. By drilling successive holes together (a process known as stitch drilling), thick concrete can be cut into any shape imaginable. Core drilling uses a diamond cutting bit to cut a perfect round hole in any concrete structure which is fast, accurate and clean. If you ever need a true deep or perfectly round hole in a concrete slab then core drilling is your best choice. Mastercut Concrete Cutting Sydney have been cutting concrete in Sydney for over 20 years and have a fleet of skilled mobile concrete cutters equipped with a range of core drills.